“The market drew support from three factors: stronger U.S. stocks, continuing ebb in strong yen concerns and the upbeat tankan,” said Masahiro Ichikawa, senior strategist at Sumitomo Mistui Asset Management.

The S&P 500 and the Nasdaq advanced to record levels on Friday while the Bank of Japan’s “tankan” survey released on Monday showed the mood among big domestic manufacturers reach a decade high.

“On the other hand, uncertainty towards how the political situation develops ahead of the election is a negative factor. The equity market will be watching how currencies respond and what kind of policies are brought up as agendas,” Ichikawa said.

Japanese Prime Minister Shinzo Abe last week dissolved the parliament’s lower house and called a snap election for Oct. 22.

Abe’s ruling Liberal Democratic Party (LDP) was initially expected to win the election with relative ease. An easy win, however, is looking less assured with popular Tokyo governor Yuriko Koike forging an alliance of opposition parties to challenge the LDP.

Shares of Nissan Motor Co dropped as much as 5.3 percent to their lowest since April 28 after the automaker said on Friday that it is unable to sell 60,000 new vehicles made in Japan as checks had been conducted by unqualified inspectors.

Ono Pharmaceutical Co advanced 3.3 percent amid speculation that a researcher that took part in developing Ono’s cancer treating drug Opdivo could win a Nobel prize this week.

Bookseller Bunkyodo Group Holdings also received a Nobel-related lift, rising 2 percent, on expectations that novelist Haruki Murakami, a perennial favourite for the literature prize, would finally win this year.

Adastria Co shed 6.9 percent after the clothing retailer revised down its net profit forecast for the year through February 2018 to 11.0 billion yen from 11.9 billion yen following lacklustre sales of summer items.